This proposal requests support for a 3 day workshop on the etiology of facial clefting. The meeting place will be the Airlie House in Virginia and participants will be invited. A panel of experts in the fields of teratology and embryology, genetics and mathematics and epidemiology will be presenting formal papers critically reviewing the current status of the literature with regard to clefts in animals and humans. The emphasis is, however, heavily on the human data. Discussants of each formal presentation will be assigned and the entire workshop discussions and papers tape-recoded. The major topic areas to be considered are: (1) animal model systems (2) human population data (3) mathematical models applied to the etiology of clefts and (4) genetic and phenotypic markers related to cleftng. The workshop will conclude with committee reports from each of these areas, and the entire group will make specific recommendations regarding the goals of future research in this area.